The invention relates to a swashplate drive, comprising a shaft rotatably journalled in a frame and carrying a plate which cooperates with one or more drive rods, each of which has a drive rod head having two spherical recess surfaces which are contacted by the spherical surface of two sliding bodies, the other, flat side of the bodies cooperating with two running surfaces on the plate, each of the running surfaces on the plate being formed by a set of straight lines, each of which extends at least substantially in a radial plane through the axis of the shaft and is tangent at each running surface to an associated torus, the center lines of the two tori being formed by two ellipses which are situated one above the other in parallel planes.
A drive of the described kind is known from Netherlands patent application No. 7,308,702 laid open to public inspection to which U.S. Pat. No. 3,968,699 corresponds. The plate in this known drive is rigidly connected to the shaft in the direction of rotation as well as in the tilting direction.
As a result of the described construction of the plate, it is achieved that the play between the plate, the sliding bodies and the recess surface is constant over the entire circumference. However, this is true for only one position of the plate relative to the shaft.
Swashplate drives are known in which the plate is tiltable relative to the shaft; see, for example, the Netherlands patent application No. 7,410,532 laid open to public inspection to which U.S. Pat. No. 4,030,404 corresponds. The stroke of the pistons connected to the piston rods in this drive can be changed by tilting of the plate. The sliding bodies in this known drive have a slightly arched surface and extend over flat, parallel running surfaces on both sides of the plate, the centers of the recesses in which the sliding bodies are accommodated being coincident. It is thus possible to keep the play between the plate, the sliding bodies and the recesses constant over the entire circumference of the plate and for all positions of the plate relative to the shaft.
However, this drive has a drawback in that the arched surfaces of the sliding bodies are subject to substantial wear, so that in this case, involving a tiltable plate, line contact between plate and sliding bodies is desirable, without introduction of excessive play variations.